CN115106428B - In-situ strengthening rapid forming method for titanium alloy thin-wall pipe - Google Patents
In-situ strengthening rapid forming method for titanium alloy thin-wall pipe Download PDFInfo
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- CN115106428B CN115106428B CN202210782025.6A CN202210782025A CN115106428B CN 115106428 B CN115106428 B CN 115106428B CN 202210782025 A CN202210782025 A CN 202210782025A CN 115106428 B CN115106428 B CN 115106428B
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- 229910001069 Ti alloy Inorganic materials 0.000 title claims abstract description 256
- 238000000034 method Methods 0.000 title claims abstract description 52
- 238000011065 in-situ storage Methods 0.000 title claims abstract description 27
- 238000005728 strengthening Methods 0.000 title claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 86
- 238000007789 sealing Methods 0.000 claims abstract description 40
- 238000001816 cooling Methods 0.000 claims abstract description 25
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 11
- 238000007599 discharging Methods 0.000 claims abstract description 9
- 230000009466 transformation Effects 0.000 claims description 15
- 230000007704 transition Effects 0.000 claims description 10
- 239000010936 titanium Substances 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 13
- 230000008569 process Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 6
- 238000011282 treatment Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
- C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
- B21D26/041—Means for controlling fluid parameters, e.g. pressure or temperature
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
- B21D26/045—Closing or sealing means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/16—Heating or cooling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Crystallography & Structural Chemistry (AREA)
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Abstract
The invention provides an in-situ strengthening and rapid forming method of a titanium alloy thin-wall pipe fitting, which comprises the following steps: placing the titanium alloy tube blank in a die at room temperature, sealing two ends, and rapidly heating the titanium alloy tube blank within 1 min; stopping heating when the temperature of the titanium alloy pipe blank reaches a set temperature, immediately introducing high-pressure gas into the titanium alloy pipe blank to enable the titanium alloy pipe blank to rapidly expand and be attached to the inner wall of a cavity of a mold, and maintaining the pressure and reducing the temperature after the air pressure reaches a set value to obtain a formed pipe fitting, wherein the pressurizing time is controlled within 2s, and the pressure maintaining time is 3-10s; and cooling the formed pipe fitting, and discharging high-pressure gas to obtain the titanium alloy thin-wall pipe fitting. The in-situ strengthening rapid forming method for the titanium alloy thin-wall pipe fitting provided by the invention can enable the formed pipe fitting to have a large amount of fine martensite structures, improves the performance of the formed pipe fitting and meets the requirements of an aircraft.
Description
Technical Field
The invention relates to the technical field of titanium alloy thin-wall pipe fitting reinforcement, in particular to a rapid in-situ reinforcement forming method for a titanium alloy thin-wall pipe fitting.
Background
With the gradual development of aircrafts towards high speed, fast response, high thrust and high reliability, the performance requirements of the titanium alloy thin-wall integral component after forming are higher and higher. However, in the conventional hot forming process of the titanium alloy thin-wall component, the titanium alloy material is heated for a long time, so that the performance of the formed component is reduced. If the heat treatment is performed after the member is formed, secondary deformation of the member may occur.
In addition, the existing titanium alloy thin-wall pipe fitting forming technology needs to heat the mold and the pipe simultaneously, when the size of the mold is large, the heating time is long, the forming efficiency is low, a special heat-resistant mold needs to be used, the mold is easy to wear, the service life is short, the production cost of the pipe fitting is high, and the requirements of the fields of aviation, aerospace and the like on high launching frequency and high reliability of an aircraft cannot be met. Therefore, the development of a titanium alloy thin-wall pipe forming process capable of strengthening the performance of the pipe in the efficient forming process and realizing synchronous control of the size precision and the performance improvement of the pipe is urgently needed.
Disclosure of Invention
The invention aims to provide a method for improving the forming efficiency of a titanium alloy thin-wall pipe fitting and improving the performance of the formed thin-wall pipe fitting.
In order to solve at least one aspect of the above problems, the present invention provides an in-situ reinforced rapid forming method for a titanium alloy thin-walled tube, comprising the following steps:
s1, placing a titanium alloy pipe blank in a die at room temperature, closing the die, and sealing the titanium alloy pipe blank in the die by using a sealing punch;
s2, rapidly heating the titanium alloy tube blank within 1 min;
s3, stopping heating when the temperature of the titanium alloy pipe blank reaches a set temperature, immediately introducing high-pressure gas into the titanium alloy pipe blank to enable the titanium alloy pipe blank to rapidly expand and be attached to the inner wall of a cavity of the mold, and obtaining a formed pipe fitting, wherein the pressurizing time is controlled within 2S, and the pressure maintaining time is 3-10S;
and S4, cooling the formed pipe fitting, and discharging the high-pressure gas in the formed pipe fitting to obtain the titanium alloy thin-wall pipe fitting.
Preferably, in the step S3, expanding and adhering the titanium alloy tube blank to the inner wall of the cavity of the mold to obtain a formed tube, the method includes: the method comprises the steps that high-pressure gas is introduced into the titanium alloy tube blank through the sealing punch, the titanium alloy tube blank is expanded and attached to the inner wall of a cavity of a die, the titanium alloy tube blank is in a high-temperature state, the die is in a room-temperature state, the die rapidly cools the expanded titanium alloy tube blank in the die to obtain a formed pipe fitting, and a large amount of fine martensite is formed inside the formed pipe fitting.
Preferably, in the step S3, the set temperature is in a range of 50 ℃ above and below the beta transformation temperature of the titanium alloy pipe blank.
Preferably, in the step S2, the heating rate is controlled to be 10-200 ℃/S.
Preferably, when the set temperature is greater than or equal to the beta transformation temperature of the titanium alloy pipe blank, the heating rate is controlled to be 50-200 ℃/s.
Preferably, in the step S3, the high-pressure gas is introduced into the mold, so that the pressure in the mold reaches 5 to 35MPa.
Preferably, when the set temperature is lower than the beta transformation temperature of the titanium alloy pipe blank, the pressure in the die reaches 10-35MPa; and when the set temperature is greater than or equal to the beta phase transition temperature of the titanium alloy pipe blank, the pressure in the die reaches 5-15MPa.
Preferably, the pressurization rate is controlled to be above 10 MPa/s.
Preferably, in the step S2, the titanium alloy tube blank is heated by current heating.
Preferably, the titanium alloy tube blank comprises one or more of TA18, TA15, TC2, TC4, TC31, ti55, ti60 and Ti 65.
The method has the advantages that the titanium alloy tube blank is rapidly heated to the set temperature, the die is kept at the room temperature, the heating time is controlled within 1min, the problem that the beta phase grows seriously due to long-time heating of the titanium alloy tube blank, the plasticity and the tensile strength of the material are influenced is avoided, the heat consumed by independently heating the titanium alloy tube blank is small, the high-temperature tube blank can be contacted with the die under the low-temperature condition after high-pressure gas is introduced into the die and the titanium alloy tube blank is expanded, the pressurizing time is controlled within 2s under the combined action of the high-pressure gas and the die, the pressure maintaining time is 3-10s, the temperature of the expanded tube blank is rapidly reduced, the quenching purpose is achieved, and the formed member has a large number of fine martensite structures due to the short time of the titanium alloy tube blank under the high-temperature condition, so that the strength of the formed member is improved; that is, the invention reduces the high temperature time of the titanium alloy tube blank in the forming process by the way of rapid heating and rapid cooling, avoids the problem of beta phase growth in the high temperature process, enables the formed tube to have a large amount of fine martensite structures, improves the performance of the formed tube, and can meet the requirements of aircrafts; in addition, the rapid in-situ strengthening forming method for the titanium alloy thin-wall pipe fitting only needs to heat the titanium alloy pipe blank and does not need to heat the die, so that the energy consumption required by heating can be obviously reduced, the forming efficiency of the titanium alloy thin-wall pipe fitting is improved, and the performance of the member is strengthened in situ while the size precision is efficiently ensured.
Drawings
FIG. 1 is a flow chart of a method for rapid in-situ strengthening forming of a titanium alloy thin-walled tube in an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a rapid in-situ strengthening forming method for a titanium alloy thin-walled tube in an embodiment of the invention;
FIG. 3 is a process diagram of the in-situ strengthening rapid forming method of the titanium alloy thin-walled tube in the embodiment of the invention;
FIG. 4 is a graph showing the structural morphology change of a titanium alloy at different heating rates according to an embodiment of the present invention;
FIG. 5 is a graph comparing strength and morphology of TC4 titanium alloy at different heating rates according to an embodiment of the present invention;
FIG. 6 is a comparison of the elongation of the Ti alloy thin-walled tube of example 5 of the present invention and the Ti60 raw material at 600 ℃;
FIG. 7 is a structural morphology of a Ti60 starting material;
fig. 8 is a structural configuration diagram of the titanium alloy thin-walled tube in example 5 of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments thereof are described in detail below.
It should be noted that the features in the embodiments of the present invention may be combined with each other without conflict. The terms "comprising," "including," "containing," and "having" are intended to be inclusive, i.e., that additional steps and other ingredients may be added without affecting the result. The above terms encompass the terms "consisting of … …" and "consisting essentially of … …". Materials, equipment and reagents were all commercially available unless otherwise specified.
In the prior art, it is generally considered that when a titanium alloy is subjected to heat treatment at a temperature near a beta transformation point, the beta phase grows seriously, so that the alpha cluster size in the treated titanium alloy is large, and the plasticity and tensile strength of the material are reduced. Therefore, the processing in the temperature range is generally avoided during the processing of the titanium alloy thin-wall part.
The embodiment of the invention provides an in-situ strengthening and rapid forming method of a titanium alloy thin-wall pipe fitting, which comprises the following steps as shown in figure 1:
s1, placing a titanium alloy pipe blank in a die at room temperature, closing the die, and sealing the titanium alloy pipe blank in the die by using a sealing punch;
s2, rapidly heating the titanium alloy tube blank within 1 min;
s3, stopping heating when the temperature of the titanium alloy pipe blank reaches a set temperature, immediately introducing high-pressure gas into the titanium alloy pipe blank to rapidly expand the titanium alloy pipe blank and attach the titanium alloy pipe blank to the inner wall of a cavity of the mold to obtain a formed pipe fitting, wherein the pressurizing time is controlled within 2S, and the pressure maintaining time is 3-10S;
and S4, cooling the formed pipe fitting, and discharging the high-pressure gas in the formed pipe fitting to obtain the titanium alloy thin-wall pipe fitting.
In the step S1, the mark of the titanium alloy tube blank comprises one or more of TA18, TA15, TC2, TC4, TC31, ti55, ti60 and Ti65, the structure form in the initial titanium alloy tube blank is an equiaxial structure, the titanium alloy tube blank is placed in a die, and the titanium alloy tube blank is sealed in the die by using a sealing punch, so that a closed space is formed inside the die. The size of the cavity of the mold is larger than that of the titanium alloy tube blank, and two ends of the titanium alloy tube blank are respectively connected with the electrodes on the mold.
Exemplarily, as shown in fig. 2, the mold is composed of an upper mold and a lower mold, and the upper mold and the lower mold are adapted to form a cavity with two narrow ends and a larger middle part after being closed; and opening the die, putting the titanium alloy tube blank into the die, closing the die, plugging two ends of the titanium alloy tube blank by the sealing punch, and sealing the titanium alloy tube blank in the die.
In the step S2, the titanium alloy tube blank is heated by current through the electrode connected with the titanium alloy tube blank, so that the temperature of the titanium alloy tube blank is raised, and the heating time is controlled within 1min in order to avoid serious growth of beta phase in the titanium alloy tube blank caused by overlong heating time. Meanwhile, the mold is not heated, so that the temperature of the mold is kept at a lower temperature.
Illustratively, as shown in fig. 2, when the die is closed, only small areas at two ends of the titanium alloy tube blank are in contact with the die, but most areas of the titanium alloy tube blank are not in contact with the die, and when the titanium alloy tube blank is directly heated, the temperature of the die is not increased remarkably, so that the titanium alloy tube blank is kept at a low temperature.
And step S3, immediately stopping heating after the temperature of the titanium alloy pipe blank reaches a set temperature, introducing high-pressure gas into the titanium alloy pipe blank through the sealing punch to expand the heated titanium alloy pipe blank until the titanium alloy pipe blank is attached to the inner wall of the cavity of the mold, wherein the temperature of the titanium alloy pipe blank is higher, the temperature of the high-pressure gas and the temperature of the inner wall of the cavity of the mold are lower, the temperature of the expanded titanium alloy pipe blank is rapidly reduced under the combined action of the high-pressure gas and the inner wall of the cavity of the mold, and the rapid cooling process in the mold is completed to obtain the formed pipe fitting. The set temperature is within the range of 50 ℃ above and below the beta transformation temperature of the titanium alloy pipe blank, a large amount of non-coarsened non-equilibrium beta phase can be formed in the heated titanium alloy pipe blank by setting the temperature within the range, when the temperature is too low, enough non-equilibrium beta phase cannot be formed, and when the temperature is too high, the beta phase is easy to overgrow, so that the performance of the formed thin-wall pipe fitting is influenced.
It should be understood that, because the beta transformation temperatures of different titanium alloy pipe blanks are different, the heating set temperature is also different, and a proper heating rate can be set, so that the heating time is kept within 1min, and the heating rate is kept within 10-200 ℃/s, wherein when the set temperature is greater than or equal to the beta transformation temperature of the titanium alloy pipe blank, the heating rate is 50-200 ℃/s.
Specifically, high-pressure gas is introduced into a die through a sealing punch, enters the heated titanium alloy tube blank, and enables the pressure in the die to reach 5-35MPa, wherein when the set temperature is lower than the beta phase transition temperature of the titanium alloy tube blank, the pressure in the die reaches 10-35MPa, and when the set temperature is higher than or equal to the beta phase transition temperature of the titanium alloy tube blank, the pressure in the die reaches 5-15MPa, because the rapidly heated titanium alloy tube blank has good plasticity, the high-pressure gas in the tube cavity of the titanium alloy tube blank is gradually increased, the internal pressure of the titanium alloy tube blank is increased, the titanium alloy tube blank expands under the action of the pressure until the titanium alloy tube blank is attached to the inner wall of the cavity of the die, the expansion is stopped, the whole pressurizing time is controlled within 2s, and the pressure maintaining time is 3-10s; and when the expanded titanium alloy pipe blank is attached to the inner wall of the cavity of the mold, the inner wall of the cavity of the mold with lower temperature quickly cools the expanded titanium alloy pipe blank to obtain the formed pipe fitting.
It is understood that the pressure after pressurization can be controlled within the range of 5-35MPa according to the material properties of different titanium alloy pipe blanks, specifically, when the set temperature is lower than the beta transformation temperature of the titanium alloy pipe blank, the pressure in the mold reaches 10-35MPa, when the set temperature is higher than or equal to the beta transformation temperature of the titanium alloy pipe blank, the pressure in the mold reaches 5-15MPa, the total pressurization time is controlled within 2s, the pressure maintaining time is 3-10s, and the pressurization speed is kept above 10 MPa.
When the pressure is set to be 5-35MPa, the titanium alloy tube blank can be expanded and attached to the inner wall of the cavity of the mold, and the titanium alloy tube blank cannot be damaged due to overlarge pressure; the pressurizing rate is controlled to be more than 10MPa, the total pressurizing time is controlled within 2s, the pressure maintaining time is controlled to be 3-10s, and the problems that the temperature of the heated titanium alloy tube blank is reduced, the plasticity of the titanium alloy tube blank is also reduced, and the tube blank is damaged in the expansion process due to overlong forming time can be avoided.
Illustratively, as shown in fig. 2, the sealing punch is communicated with the inner ring of the titanium alloy tube blank, high-pressure gas is injected into the die through the sealing punch, so that the high-pressure gas enters the heated titanium alloy tube blank, and because the heated titanium alloy tube blank has good plasticity, when the high-pressure gas is injected continuously and the pressure in the titanium alloy tube blank is increased continuously, the titanium alloy tube blank expands until the titanium alloy tube blank is attached to the inner wall of the cavity of the die, so that the shaping of the titanium alloy tube blank is completed, and the formed pipe fitting is obtained.
And S4, after the pipe fitting is formed, exhausting the high-pressure gas in the formed pipe fitting, and cooling the formed pipe fitting to obtain the titanium alloy thin-wall pipe fitting.
Fig. 3 is a process curve diagram of the titanium alloy thin-walled tube in-situ strengthening rapid forming method in the embodiment of the invention, wherein the abscissa in fig. 3 represents time, the left ordinate represents temperature, and the right ordinate represents air pressure.
As can be seen from fig. 3, after the titanium alloy tube blank is rapidly heated, the titanium alloy tube blank is rapidly raised to the temperature T, then high-pressure gas is immediately introduced to rapidly pressurize to the pressure p, so that the titanium alloy tube blank rapidly expands, after the pressure in the titanium alloy tube blank is kept at the pressure p for a period of time, the titanium alloy tube blank is rapidly cooled in the die to the room temperature, then the pressure is relieved, and the titanium alloy tube blank is rapidly formed by in-situ strengthening; 0-t in FIG. 3 0 The time period is heating time, the heating time is controlled within 1min, t 0 -t 1 The time period is pressurizing time, the pressurizing time is controlled within 2s, t 1 -t 2 The time period is the pressure maintaining time which is 3-10s.
FIG. 4 is a comparison of the change of the texture in the tube blank at different heating rates, wherein when the tube blank is rapidly heated (the total heating time is less than or equal to 1 min), a large amount of non-coarsened nonequilibrium beta-phase is formed in the heated tube blank, and a large amount of fine martensite is formed after rapid cooling, so that the strength of the formed tube is improved; when the pipe blank is heated slowly (the total heating time is more than 1 min), the beta phase in the heated pipe blank grows seriously, and large martensite is formed after the pipe blank is cooled quickly, so that the strength of the formed pipe fitting is low. It should be noted that, in order to simplify the comparison of the effects at different heating rates, fig. 4 only shows the evolution of the β -phase region structure in the tube blank during heating, and in the practical process, when the heating temperature is slightly lower than the β -phase transformation point, the formed tube further contains a small amount of primary α -phase structure.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are examples of experimental procedures not specified under specific conditions, generally according to the conditions recommended by the manufacturer.
Example 1
The embodiment provides an in-situ strengthening and rapid forming method for a titanium alloy thin-wall pipe fitting, which comprises the following steps of:
1.1, placing a TC4 titanium alloy tube blank in a die, and sealing the die by adopting a sealing punch;
1.2, heating the TC4 titanium alloy pipe blank to 1000 ℃ (the beta phase transition temperature of TC4 is 990 ℃), the heating rate is 50 ℃/s, the heating time is 20s, and the mold is kept at the room temperature;
1.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 1000 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 12MPa, maintaining the pressure for 5 seconds to ensure that the TC4 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 15MPa/s, and the pressurizing time is 0.8s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
and 1.4, exhausting high-pressure gas in the TC4 titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Example 2
The embodiment provides an in-situ strengthening and rapid forming method for a titanium alloy thin-wall pipe fitting, which comprises the following steps of:
2.1, placing the TC4 titanium alloy tube blank in a die, and sealing the die by adopting a sealing punch;
2.2, heating the TC4 titanium alloy tube blank to 1000 ℃ (the beta transformation temperature of TC4 is 990 ℃), the heating rate is 100 ℃/s, the heating time is 10s, and the mold is kept at the room temperature;
2.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 1000 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 12MPa, maintaining the pressure for 5 seconds to ensure that the TC4 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 15MPa/s, and the pressurizing time is 0.8s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
and 2.4, discharging high-pressure gas introduced into the TC4 titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Example 3
The embodiment provides an in-situ strengthening and rapid forming method of a titanium alloy thin-wall pipe fitting, which comprises the following steps:
3.1, placing the TC4 titanium alloy tube blank in a die, and sealing the die by adopting a sealing punch;
3.2, heating the TC4 titanium alloy tube blank to 1030 ℃ (the beta transformation temperature of TC4 is 990 ℃), wherein the heating rate is 100 ℃/s, the heating time is 10.3s, and the mold is kept at the room temperature;
3.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 1000 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 5MPa, maintaining the pressure for 10 seconds to ensure that the TC4 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 10MPa/s, and the pressurizing time is 0.5s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
and 3.4, exhausting high-pressure gas in the TC4 titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Example 4
The embodiment provides an in-situ strengthening and rapid forming method of a titanium alloy thin-wall pipe fitting, which comprises the following steps:
4.1, placing the TC4 titanium alloy tube blank in a die, and sealing the die by using a sealing punch;
4.2, heating the TC4 titanium alloy pipe blank to 950 ℃ (the beta transformation temperature of TC4 is 990 ℃), the heating rate is 100 ℃/s, the heating time is 9.5s, and the mold is kept at the room temperature;
4.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 950 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to enable the air pressure in the mould to reach 35MPa, maintaining the pressure for 3 seconds to enable the TC4 titanium alloy tube blank to expand and be attached to a cavity of the mould, wherein the pressurizing speed is 20MPa/s, and the pressurizing time is 1.8s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, rapid cooling in the mould is completed, and a formed pipe fitting is obtained;
and 4.4, discharging the high-pressure gas introduced into the TC4 titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Example 5
The embodiment provides an in-situ strengthening and rapid forming method of a titanium alloy thin-wall pipe fitting, which comprises the following steps:
5.1, placing the Ti60 titanium alloy tube blank in a die, and sealing the die by adopting a sealing punch;
5.2, heating the Ti60 titanium alloy pipe blank to 1050 ℃ (the beta phase transition temperature of Ti60 is 1040 ℃), the heating rate is 100 ℃/s, the heating time is 10.5s, and the mould is kept at the room temperature;
5.3, immediately stopping heating when the temperature of the Ti60 titanium alloy tube blank reaches 1050 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 12MPa, maintaining the pressure for 5 seconds to ensure that the Ti60 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 20MPa/s, and the pressurizing time is 0.6s, when the expanded Ti60 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the Ti60 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
and 5.4, discharging high-pressure gas introduced into the Ti60 titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Comparative example 1
The embodiment provides an in-situ strengthening and rapid forming method of a titanium alloy thin-wall pipe fitting, which comprises the following steps:
6.1, placing the TC4 titanium alloy tube blank in a die, and sealing the die by adopting a sealing punch;
6.2, heating the TC4 titanium alloy pipe blank to 1000 ℃ (the beta phase transition temperature of TC4 is 990 ℃), the heating rate is 2 ℃/s, the heating time is 500s, and the mold is kept at the room temperature;
6.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 1000 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 12MPa, maintaining the pressure for 5 seconds to ensure that the TC4 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 15MPa/s, and the pressurizing time is 0.8s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
and 6.4, discharging high-pressure gas introduced into the titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Comparative example 2
The embodiment provides an in-situ strengthening and rapid forming method for a titanium alloy thin-wall pipe fitting, which comprises the following steps of:
7.1, placing the TC4 titanium alloy tube blank in a die, and sealing the die by using a sealing punch;
7.2, heating the TC4 titanium alloy pipe blank to 1000 ℃ (the beta transformation temperature of TC4 is 990 ℃), the heating rate is 15 ℃/s, the heating time is 67s, and the mold is kept at the room temperature;
7.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 1000 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 12MPa, maintaining the pressure for 5 seconds to ensure that the TC4 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 15MPa/s, and the pressurizing time is 0.8s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
7.4, exhausting high-pressure gas in the titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Comparative example 3
The embodiment provides an in-situ strengthening and rapid forming method for a titanium alloy thin-wall pipe fitting, which comprises the following steps of:
8.1, placing the TC4 titanium alloy tube blank in a die, and sealing the die by using a sealing punch;
8.2, heating the TC4 titanium alloy tube blank to 1000 ℃ (the beta phase transition temperature of TC4 is 990 ℃), the heating rate is 100 ℃/s, the heating time is 10s, the mold is kept at the room temperature, and the temperature is kept for 120s after heating;
8.3, immediately stopping heating when the temperature of the TC4 titanium alloy tube blank reaches 1000 ℃, introducing high-pressure gas into the titanium alloy tube blank through a sealing punch to ensure that the air pressure in the mould reaches 12MPa, maintaining the pressure for 5 seconds to ensure that the TC4 titanium alloy tube blank expands and is attached to a cavity of the mould, wherein the pressurizing rate is 15MPa/s, and the pressurizing time is 0.8s, when the expanded TC4 titanium alloy tube blank contacts the mould cavity at room temperature, the temperature of the TC4 titanium alloy tube blank is rapidly reduced, and rapid cooling in the mould is completed to obtain a formed pipe fitting;
8.4, discharging high-pressure gas introduced into the titanium alloy pipe blank, cooling the formed pipe fitting, and opening the die to obtain the titanium alloy thin-wall pipe fitting.
Experimental example 1
The strength and elongation of the TC4 titanium alloy starting material and the titanium alloy thin-walled tube fabricated by the methods of examples 1 to 2 and comparative examples 1 to 3, and the texture of the titanium alloy thin-walled tube fabricated by the methods of example 2, comparative example 1 and comparative example 3 were measured.
The measurement results are shown in fig. 5, wherein (a) in fig. 5 is a comparison graph of strength and elongation at different treatments, and (b) in fig. 5, (c) in fig. 5 and (d) in fig. 5 are the structure morphology of the titanium alloy thin-walled tube prepared by the methods of example 2, comparative example 1 and comparative example 3 respectively; in fig. 5 (a), the original indicates TC4 original material, 2 ℃/s indicates the titanium alloy thin-walled tube manufactured by the method of comparative example 1, 15 ℃/s indicates the titanium alloy thin-walled tube manufactured by the method of comparative example 2, 50 ℃/s indicates the titanium alloy thin-walled tube manufactured by the method of example 1, 100 ℃/s indicates the titanium alloy thin-walled tube manufactured by the method of example 2, and 100 ℃/s-120s indicates the titanium alloy thin-walled tube manufactured by the method of comparative example 3, as can be seen from fig. 5 (a), when the heating time is controlled within 1min, and the strength of the titanium alloy thin-walled tube which is not subjected to the heat preservation treatment after heating is significantly improved, 10% -20% is improved compared with the original material and comparative examples 1-3, and the elongation of the titanium alloy thin-walled tubes manufactured by the examples 1 and 2 is not lower than 7%; as can be seen from fig. 5 (b), fig. 5 (c) and fig. 5 (d), the heating rate is 100 ℃/s, the heating time is controlled within 1min, and the titanium alloy thin-walled tube which is not subjected to the heat preservation treatment after heating contains more fine martensite, so that the performance can be improved, while the titanium alloy thin-walled tubes of comparative examples 1 and 3 generate martensite, but the martensite is larger, and the performance is relatively poor.
According to the graph 5, when the heating rate is high and the total heating time is within 1min, the material strength of the obtained titanium alloy thin-wall pipe is obviously improved, and the elongation is high, which shows that the titanium alloy thin-wall pipe has high strength and plasticity and excellent performance; and the heating rate is low, or the total heating time is more than 1min due to heat preservation treatment after heating, so that the reinforcing effect of the obtained titanium alloy thin-wall pipe fitting is weakened, and the plasticity is reduced. This is mainly because when the heating time is longer, the beta phase will grow up, which affects the performance of the titanium alloy thin-wall pipe.
Experimental example 2
The strength and elongation at 600 ℃ of the Ti60 titanium alloy starting material and the thin-walled titanium alloy tube obtained by the method of example 5 were measured and compared in terms of the structure.
The results are shown in FIGS. 6 to 8, in which FIG. 6 is a graph showing the comparison of strength and elongation properties, the initial state of the graph is Ti60 titanium alloy raw material, 1050 to 100 ℃/s is titanium alloy thin-walled tube processed by heating to 1050 ℃ at a heating rate of 100 ℃/s in example 5, FIG. 7 is a structural morphology graph of Ti60 titanium alloy raw material, and FIG. 8 is a structural morphology graph of titanium alloy thin-walled tube processed by the method of example 5.
As can be seen from fig. 6, the tensile strength of the Ti60 titanium alloy raw material at 600 ℃ is 696.11MPa, while the tensile strength of the titanium alloy thin-wall tube obtained by the method of example 5 at 600 ℃ is 968.68 ℃, which is 39.16% higher than that of the Ti60 titanium alloy raw material; the elongation of the Ti60 titanium alloy raw material at 600 ℃ is 25.92%, and the elongation of the titanium alloy thin-wall pipe obtained by the method of the example 5 at 600 ℃ is 13.05%.
In addition, as can be seen from fig. 7 and 8, a large amount of fine martensite exists in the titanium alloy thin-wall pipe obtained by the method of the embodiment 5, so that the high-temperature performance of the material is remarkably improved.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the disclosure, and these changes and modifications are intended to fall within the scope of the invention.
Claims (5)
1. The in-situ strengthening rapid forming method of the titanium alloy thin-wall pipe is characterized by comprising the following steps of:
s1, placing a titanium alloy pipe blank in a die at room temperature, closing the die, and sealing the titanium alloy pipe blank in the die by using a sealing punch;
s2, rapidly heating the titanium alloy tube blank within 1 min;
s3, stopping heating when the temperature of the titanium alloy pipe blank reaches a set temperature, immediately introducing high-pressure gas into the titanium alloy pipe blank to enable the titanium alloy pipe blank to rapidly expand and be attached to the inner wall of a cavity of the mold, and maintaining the pressure and reducing the temperature after the air pressure reaches the set value to obtain a formed pipe fitting, wherein the pressurizing time is controlled within 2S, and the maintaining time is 3-10S;
s4, cooling the formed pipe fitting, and discharging the high-pressure gas in the formed pipe fitting to obtain a titanium alloy thin-wall pipe fitting;
wherein in the step S2, the heating rate is controlled to be 10-200 ℃/S; when the set temperature is greater than or equal to the beta phase transition temperature of the titanium alloy pipe blank, the heating rate is controlled to be 50-200 ℃/s;
in the step S3, the set temperature is within the range of 50 ℃ above and below the beta transformation temperature of the titanium alloy tube blank;
when the set temperature is lower than the beta phase transition temperature of the titanium alloy pipe blank, the pressure in the die reaches 10-35MPa; and when the set temperature is greater than or equal to the beta phase transition temperature of the titanium alloy pipe blank, the pressure in the die reaches 5-15MPa.
2. The in-situ strengthening rapid forming method for the titanium alloy thin-walled tube part according to claim 1, wherein in the step S3, the expanding and adhering the titanium alloy tube blank to the inner wall of the cavity of the mold to obtain the formed tube part comprises:
the sealing punch is used for introducing high-pressure gas into the titanium alloy tube blank, so that the titanium alloy tube blank expands and is attached to the inner wall of a cavity of the die, the titanium alloy tube blank is in a high-temperature state, the die is in a low-temperature state, the die is used for rapidly cooling the expanded titanium alloy tube blank in the die to obtain a formed pipe fitting, and a large amount of fine martensite is formed inside the formed pipe fitting.
3. The in-situ reinforced rapid forming method for the titanium alloy thin-wall pipe fitting as claimed in claim 1, wherein the pressurizing rate is controlled to be above 10 MPa/s.
4. The in-situ strengthening rapid forming method for the titanium alloy thin-walled tube part according to claim 1, characterized in that in the step S2, the titanium alloy tube blank is heated by means of current heating.
5. The in-situ strengthening rapid forming method for the titanium alloy thin-wall pipe fitting according to claim 1, wherein the titanium alloy pipe blank comprises one or more of TA18, TA15, TC2, TC4, TC31, ti55, ti60 and Ti 65.
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| CN202210782025.6A CN115106428B (en) | 2022-07-04 | 2022-07-04 | In-situ strengthening rapid forming method for titanium alloy thin-wall pipe |
| US18/048,523 US20240002988A1 (en) | 2022-07-04 | 2022-10-21 | In-situ strengthening and rapid forming method for thin-walled titanium alloy tubular component |
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| DE102007018395B4 (en) * | 2007-04-17 | 2011-02-17 | Benteler Automobiltechnik Gmbh | Internal high-pressure forming |
| CN102248058B (en) * | 2011-06-20 | 2013-08-28 | 哈尔滨工业大学（威海） | Process method for improving high pressure forming limit in tube |
| CN102641936A (en) * | 2012-05-08 | 2012-08-22 | 哈尔滨工业大学 | Tubing bulging device and method using internal heating and pressing |
| CN106513508A (en) * | 2016-09-23 | 2017-03-22 | 北京航空航天大学 | Titanium alloy sheet metal part cold-die hot-stamping forming tool and machining method |
| CN107199270A (en) * | 2017-03-28 | 2017-09-26 | 华侨大学 | A kind of apparatus and method for high-strength steel tubing gas bulging |
| CN109465322A (en) * | 2018-11-09 | 2019-03-15 | 南京航空航天大学 | A kind of pulse current pulsating heating gas pressure compacting device and method of less-deformable alloy pipe fitting |
| CN110252899B (en) * | 2019-07-25 | 2021-07-02 | 哈尔滨工业大学 | Rapid heating cold die hot plate forming method for titanium alloy thin-wall component |
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